1. Field of the Invention
The present invention relates to a vertical engine including a crankshaft disposed in a generally vertical direction, and to an outboard engine system including such a vertical engine mounted thereon.
2. Description of the Related Art
Japanese Patent Application Laid-open No. 11-148329 discloses an outboard engine system having a vertical engine mounted thereon in which an oil passage for supplying an oil from an oil pan to an oil filter mounted on a side of a cylinder block is formed in a wall surface of the cylinder block by withdrawing a core pin during formation of the cylinder block in die-casting, or formed by drilling after the formation of the cylinder block.
In the outboard engine system described in the above-described Japanese Patent Application Laid-open No. 11-148329, the oil passage is provided utilizing a portion of a wall forming a section for accommodating a balancer shaft. In an engine having no balancer shaft disposed in a lateral direction of a cylinder, however, in order to form an oil passage having a predetermined inner diameter in a wall surface of a cylinder block and hence, it is necessary to form the entire wall surface of the cylinder block at an increased thickness or to form an bulged portion around the oil passage. For this reason, a useless wall portion is created to increase the weight of the cylinder block, and also there is a fear that the disposition of the oil passage is restrained by the shape of the cylinder block, resulting in a decrease in degree of freedom for a layout.
The oil supplied to portions to be lubricated of the engine bears a cooling function in addition to a lubricating function, and it is desirable that the oil having a temperature as low as possible is supplied to the portions to be lubricated. In the outboard engine system described in the above-described publications, it is difficult to extend a water jacket to the vicinity of a mounting seat of the oil filter supported in the cylinder block, and hence it is difficult to further cool the oil in the oil filter.